Patent GB-274859-A (GB)
Title: New or improved method and apparatus for finishing or rectifying meshing parts and particularly gear teeth
IPC: B23F19/04
Filed: 1927-07-18
Abstract: 274,859. Lees-Bradner Co., (Assignees of Schurr, C. H.). July 21, 1926, [Convention date]. Rolling wheels; die-rolling. - In a method of finishing the teeth of roughed-out gears or the projections or lobes of machine parts, the work is rolled in mesh with a tool having accurately formed and spaced teeth &c., axial feed being imparted to the work or tool so that the tool moves progressively over the teeth in axial direction and redistributes the metal on the surfaces of the rough teeth to produce accurate teeth with hardened working faces. In one form, a frame 1 is bored to receive a number of tool-spindles 3 carrying accurately-cut tools 5 - - 8 which are spaced around the rough-cut blank 15 mounted on a central spindle 11. The frame 1 may be moved axially of the blank to carry the tools over the tooth surfaces, and the tools are all driven from a long pinion 13 on the blank spindle which engages gears 4. The gears 4 and 13 have accurately cut teeth and the tools are rotated relatively to the blank at their correct meshing speeds and are maintained at fixed radial distances from the blank axis. The upper ends of the teeth on the tools are preferably chamfered at 23, Fig. 8. In operation, as the rotating tools in meshing engagement with the work are advanced axially, the teeth 20 of the tools redistribute the outer layer of metal on the blank teeth and finally produce teeth on the blank which are accurate as to pitch, profile and concentricity and have increased hardness, density &c. Some of the metal of the blank teeth may be moved forward by the chamfered tool edge in the form of a ridge 24, Fig. 8, and this surplus metal may form ridges along the outer ends of the finished teeth. These ridges may either be removed by a subsequent operation or may be left on the gear. The normal axial feed of the tools may be of the order of 5/1000‹ per revolution of the blank. The steepness and shape of the tooth chamfer may be modified in various ways and in some cases the teeth may have only a small finished portion 27, Fig. 14, chamfered off in both directions. Such a tool may be passed through the blank in either direction. If only one tool is employed, the engagement between tool and work will, on the pitch line, be of a purely rolling character without slipping and in order to render the action equally effective on all parts of the blank tooth profile, the teeth of the tools are preferably made of different pressure angles as shown in Fig. 3. The different tools thus engage the blank on pitch circles 35, 37, 39, 41, which are spaced at various distances from the. base circle 34 of the blank teeth. In a modification, the tools may have successively larger diameters but are provided with teeth having base circles of the same diameter. In another modification, the work spindle may remain stationary and the tool spindles revolved about it. Other arrangements of one or more tool-spindles and the work-spindle may be employed. Fig. 20 shows an example of a lobed form to which the invention is applicable.